Punch clamping mechanism for power presses



April 3, 1962 F. J. HOHL Filed Sept. 16, 1957 Fig.1.

I I l 11 1: 2:35 11 Q '11 4M m 22%, 4 L a INVENTOR. Frank J. hohl,

V I ATTORNEYS.

F J. HOHL PUNCH CLAMPING MECHANISM FOR POWER PRESSES 2 Sheets-Sheet 2 INVENTOR. Fmnfrlhbh],

ATTORNEYS April 3, 1962 Filed Sept. 16, 1957 FJ'Q3.

This invention relates to means for quickly clamping the punch assembly of a conventional die mechanism to the upper platen or slide of a power press.

Stated generally, the present invention comprises means whereby the reciprocable slide of a power press may be brought down to the top surface of a die assembly, that is, to the top of the punch unit or reciprocable portion of a die mechanism, after the die assembly has been properly secured to the bed of the power press, for quickly and securely clamping the punch unit to the slide in a readily releasable manner for reciprocation thereby.

Although not limited thereto in use, the present invention is particularly advantageous when employed in conjunction with power presses which are adapted for quick die changes by means of so-called sliding bolsters. In such presses the bolster which comprises the die-receiving bed of the press is roughly twice as wide as in conventional presses and is mounted for lateral sliding or rolling movement so that, while one half is in working position beneath the slide of the press, and the press is in actual operation with a die mounted upon such half of the bolster, the other half is exposed at the side of the press so that a die assembly which is to be used subsequently may be positioned thereon and bolted thereto in the usual manner.

Power means are provided for shifting the bolster to remove one die laterally from beneath the slide of the press and position the other for subsequent operation. However, before the bolster shifting operation it is necessary to release the punch portion of the die which has been used from the slide or platen of the press, and after the bolster shifting operation it is necessary to secure the punch portion of the new die to the slide or platen. It is in this portion of die changing that the arrangement of the present invention enters the picture.

The present invention provides an arrangement wherein the release of a punch unit of a die assembly from the slide, platen or ram of a power press and subsequent securement of a new punch unit in place thereof is purely a push-button operation. Speaking generally, it is merely necessary, after a die assembly is properly positioned, to inc the slide of the press down to the top surface of the punch and operate a push-button controlled fluid pressure valve which automatically clamps the punch unit securely to the bottom of the slide. Release of the punch unit after completion of a run merely requires a reverse push-button operation.

The aforesaid push-button operation automatically brings clamp members into proper clamping position with respect to the punch unit and tightens the same. Furthermore, while the operation is performed by hydraulic pressure, clamping force, once applied, is maintained by mechanical friction and the hydraulic pressure need not be maintained to retain the parts in secure clamping condition between clamping and unclamping operations.

A single specific embodiment of the principles of the present invention is illustrated in the accompanying drawings and described in detail in the following specification. However, it is to be understood that such embodiment is by way of example only and that the principles of the present invention are not limited thereto or otherwise than as defined in the appended claims.

In the drawings:

FIG. 1 is a general top plan view of one form of the ited States Patent 7 3,027,792 Patented Apr. 3, 1962 2 clamping mechanism of the present invention with the slide of a power press shown partly in cross section;

FIG. 2 is a cross-sectional view taken as indicated by the line II-II of FIG. 1;

FIG. 3 is a fragmentary cross-sectional view taken approximately on the line lIL-III of FIG. 2; and

FIG. 4 is a view similar to FIG. 3 but with the clamping member in a released position.

Like characters of reference denote like parts throughout the several figures of the drawings and the numeral 10 designates the vertically reciprocable slide of a conventional power press, the vertical guides thereof being designated by the numeral 11 in FIG. 1. As is conventional in power press construction, slide 10 is provided with forwardly and rearwardly directed horizontal flange portions 11 and 12 which, together with the bottom surface of the slide proper, form a downwardly facing platen surface 13 of substantial area against which the reciprocable punch portion of a die assembly is commonly secured. This securement is conventionally accomplished by screws or bolts engaging between the platen of the slide and the punch holder of the punch portion of the die assembly, the bottom surface or platen of the slide being commonly T-slotted for this purpose.

In pursuing the principles of the present invention, front and rear clamp mechanisms designated generally by the numerals 14 and 15, respectively, are mounted upon the flange formations 11 and 12, respectively, of the slide 10.

The front and rear clamp mechanisms 14 and 15 are identical and a detailed description of one will suflice for both, like characters of reference being applied to corresponding parts of each. Referring particularly to FIG. 2, an elongated mounting block 20 of angular cross section is secured against the top surface and outer edge of flange 11 by screws 21 and a companion block 22 is secured to the upper surface of mounting block 20 by screws 23.

Each of the clamp mechanisms is provided with a pair of shaft members 26 which are journalled in bushings 27 in the mounting block 20 and in roller bearings 28 in the companion block 22. Between the bushings 27 and the roller bearings 28 the shafts are formed with pinions 30 for cooperation with rack members 31 in a manner which will presently appear. The lower ends of the shaft members 26 are threaded as at 33 and these threads engage internal threads in annular clamp members 34 which have lateral clamping extensions 35.

Mounting block 20 and companion block 22 are hollowed out as at 36 to receive a hydraulic cylinder 37 which in the present instance is provided with a pair of pistons 38, each of which has a piston rod 39 projecting outwardly therefrom for engagement with one of the rack members 31.

Hydraulic fluid pressure is simultaneously applied to ports 41 at opposite ends of hydraulic cylinder 37 for applying a clamping force in a manner which will presently appear and the pistons 38 are operated in a reverse direction by hydraulic pressure applied to a port 42 midway of the hydraulic cylinder 37 for effecting unclamping movement. In the present instance the ends of hydraulic cylinder 37 comprise rectangular blocks 43 which, as appears at the right-hand side of FIG. 2, are mounted against companion block 22 by screws 44.

Referring to FIG. 2, an adapter plate 45 of predetermined thickness and horizontal expanse is secured to the top surface of a punch holder that is to be attached to slide 10 by screws or the like and in FIG. 2 the punch holder is indicated more or less schematically in dot and dash lines at 46.

FIGS. 1 and 2 of the drawings illustrate the clamping mechanisms in clamping position and the operation will therefore be described beginning with a position wherein adapter plate 45 is clamped between the clamping extensions 35 of the clamping members 34 and the under side or platen surface 13 of slide To unclamp punch holder 46 and its adapter plate -45, hydraulic pressure is applied to the passages 42 of the cylinders 37 which moves the several pistons 3S outwardly or apart from each other and moves the rack members 31 apart from each other.

The threads 33 of the lower left hand and upper right hand shaft members 26, as viewed in FIG. 1, are left hand threads, and the threads .33 of the upper left hand and lower right hand shaft members are right hand.

Outward movement of the rack members 31, as described in the preceding paragraph, causes the upper left hand shaft member 26 and the lower right hand shaft member 26, as viewed in FIG. 1, to tend to rotate in a counterclockwise direction and causes the upper right hand shaft member 26 and the lower left hand shaft member 26' to tend to rotate in a clockwise direction.

However, since the clamping extensions are in firm clamping engagement with the under side of the adapter plate 45, the first rotative movement of the shafts 26 produces an unscrewing movement as between the threaded portions 33 of such shafts and the internal threads of the clamp members 34, whereby the several clamp members 34 move downward as viewed in FIG. 2 until the clamping extensions 35 are relieved-from clamping and frictional engagement with adapter plate 45.

After this frictional contact is relieved the several clamp members 34 rotate with their mounting shaft members 26 to swing outwardly to disengaged positions, as illustrated in FIG. 4.

Rotation of the clamp members 34 in opposite directions between the clamping and non-clamping positions thereof is limited to approximately 90 degrees in either direction by stop means best shown in FIGS. 3 and 4. Referring first to FIG. 2, the lower ends of bushings 27 are disposed in bosses 47 which project downwardly from the mounting block-s 20. The lower faces of the bosses 47 are arcuately notched as at 48, and stop lugs 49 on the clamp members 34 engage the opposite ends of the notches 48 to limit rotative movement of the clamp members.

The axial thrust engendered by clamping is borne by axial thrust anti-friction bearings 50 which transfer the axial clamping thrust from the lower faces of the pinion formations 30 to the upper ends of the bushings 27.

Clamping action, after a die is moved into a desired operative position beneath slide 10, is effected by applying hydraulic fluid pressure to the passages 41 which moves the rack members 31 relatively toward each other. During this movement of the rack members 31 the clamp members 34 turn with their respective shaft members 26 from the position of FIG. 4 to the position of FIG. 3. As the stop lug 49 of each clamp member 34 reaches an end of notch 48 and its turning movement is arrested, the threaded portions 33 of the shaft members turn in the clamp members 34 and draw them up into clamping relation, the tightness of such clamping being determined by the magnitude of the hydraulic pressure force.

After the clamping operation is completed, hydraulic pressure need not be maintained, since the clamped condition is frictionally maintained by the screw thread engagement between the shaft members 26 and the clamp members 34. This provides a more certain, safe and effective clamp than one which depends on the maintenance of pressure during the entire clamping period, and is also simpler and more economical.

What is claimed is:

1. In a power press, a platen and means for securing a die member thereagainst, said die member having portionsprojecting laterally from opposite sides thereof, said securing means comprising clamp supporting members fixed to opposite sides of said platen, each clamp supporting member having a pair of rotatable threaded members spaced ther'ealong, correspondingly threaded clamp members supported on'said threaded members and having laterally projecting clamp portions, said clam-p members being rotatable jointly with said threaded members between clamping and non-clamping positions with respect to said laterally projecting die member portions, means arresting rotation of said clamp members in clamping position, and fluid pressure motor means for rotating the several threaded members for swinging the supported clamp members to clamping positions and thereafter drawing them against said die member projecting portions to clamp the same against said platen.

2. In a power press, a platen and means for securing a die member thereagainst, said die member having portions projecting laterally from opposite sides thereof, said securing means comprising clamp supporting members fixed to opposite sides of said platen, each clamp supporting member having a rotatable threaded member, a correspondingly threaded clamp member supported on said threaded member and having a laterally projecting clamp portion, said clamp member being rotatable jointly with said threaded member between clamping and non-clamping positions with respect to a laterally projecting die member portion, means arresting rotation of said clamp members in clamping position, and fluid pressure motor means for rotating the threaded members of said clamp supporting members for swinging the supported clamp members to clamping positions and thereafter drawing them against said die member projecting portions to clamp the same against said platen.

3. In a power press, a platen and means for clamping a die member thereagainst, said die member having laterally projecting means adapted to, be clamped to said platen, said clamping means comprising clamp supporting means fixed to said platen, said clamp supporting means having-a plurality of rotatable threaded members, correspondingly threaded clamp members supported on said threaded members and having laterally projecting clamp portions, said clamp members being rotatable jointly with said threaded members between clamping and non-clamping positions with respect to said laterally projecting die member means, means arresting rotation of said clamp members in clamping position, and fluid pressure motor means for rotating the threaded members for swinging the supported clamp members to clamping positions and thereafter drawing them against said die member projecting means to clamp the same against said platen.

4. In a power press, a platen and means for securing a die member thereagainst, said die member having portions projecting laterally from opposite sides thereof, said securing means comprising clamp supporting members fixed to opposite sides of said platen, each clamp supporting member having a pair of rotatable threaded members spaced therealong and fluid pressure piston and cylinder means disposed generally between said threaded members, rack members at opposite ends of said piston and cylinder means and adapted to be projected and retracted thereby, pinions on said threaded members meshing with said rack members to be rotated thereby, correspondingly threaded clamp members supported on said threaded members and having laterally projecting clamp portions, said clamp members being rotatable with said threaded members between clamping and non-clamping positions with respect to said laterally projecting die member portions by actuation of said rack members, means arresting rotation of said clamp members in clamping position, said fluid pressure means being thereby operable to simultaneously rotate the several threaded members to swing the supported clamp members to clamping positions and thereafter draw them against said die member projecting portions to clamp the same against said platen.

5. In a power press, a platen and means for securing a die member thereagainst, said die member having laterally projecting means adapted to be clamped to said platen, said securing means including a clamp supporting member fixed to a side of said platen, said clamp supporting member having a pair of rotatable threaded members spaced therealong and fluid pressure piston and cylinder means disposed generally between said threaded members, rack members at opposite ends of said piston and cylinder means and adapted to be projected and retracted thereby, pinions on said threaded members meshing with said rack members to be rotated thereby, correspondingly threaded clamp members supported on said threaded members and having laterally projecting clamp portions, said clamp members being rotatable with said threaded members between clamping and non-clamping positions with respect to said die member projecting means by actuation of said rack members, means arresting rotation of said clamp members in clamping position, said fluid pressure means being thereby operable to simultaneously rotate the several threaded members to swing the supported clamp members to clamping positions and thereafter draw them against said die member projecting means to clamp the same against said platen.

6. in a power press, a platen and means for securing a die member thereagainst, said die member having laterally projecting means adapted to be clamped to said platen, said securing means comprising a clamp supporting member fixed to said platen, said clamp supporting member having a rotatable threaded member and fluid pressure piston and cylinder means 'for rotating the same, a rack member at an end of said piston and cylinder means and adapted to be projected and retracted thereby, a pinion on said threaded member meshing with said rack member, a correspondingly threaded clamp member supported on said threaded member and having a laterally projecting clamp portion, said clamp member being rotatable with said threaded members between clamping and non-clamping positions with respect to said laterally projecting die member means by actuation of said rack member, means arresting rotation of said clamp member in clamping position, said fluid pressure means being thereby operable to rotate the threaded member to swing the supported clamp member to clamping position and thereafter draw the same against said die member projecting means to clamp the same against said platen.

7. 'In a power press, a platen and means for securing a die member thereagainst, said die member having portions projecting laterally from opposite sides thereof, said securing means comprising clamp supporting members fixed to opposite sides of said platen, each clamp supporting member having a pair of rotatable threaded members spaced therealong, rack means and pinions on said threaded members meshing with said rack means to be rotated thereby, correspondingly threaded clamp members supported on said threaded members and having laterally projecting clamp portions, said clamp members being rotatable with said threaded members between clamping and non-clamping positions with respect to said laterally projecting die member portions by actuation of said rack members, mean-s arresting rotation of said clamp members in clamping position, and motor means for moving said rack means to simultaneously rotate the several threaded members to swing the supported clam-p members to clamping positions and thereafter draw them against said die member projecting portions to clamp the same against said platen.

8. In a power press, a platen and means for securing a die member thereagainst, said die member having laterally projecting means adapted to be clamped to said platen, said securing means including a clamp supporting member fixed to a side of said platen, said clamp supporting member having a threaded member mounted for rotation on an axis perpendicular to said platen, rack means and a pinion on said threaded member meshing with said rack means to be rotated thereby, a correspondingly threaded clamp member supported on said threaded member and having a laterally projecting clamp portion, said clamp member being rotatable with said threaded member between clamping and non-clamping positions with respect to said laterally projecting die member means by actuation of said rack members, means arresting rotation of said clamp member in clamping position, and motor means for moving said rack means to rotate the threaded member to swing the supported clamp member to clamping position and thereafter draw the same again-st said die member projecting means to clamp the same against said platen.

9. In a power press, a reciprocable platen and means for securing a punch holder against the under surface thereof, said punch holder including portions projecting horizontally from opposite sides thereof, said securing means comprising clamp supporting members fixed to opposite sides of said platen, each clamp member having a pair of screw members spaced therealong and projecting downwardly therefrom, internally threaded clamp members supported on said screws and having horizontally projecting clamp portions, said clamp members being rotatable jointly with said screw members between clamping and non-clamping positions, means arresting rotation of said clamp members in clamping position, and fluid pressure motor means for simultaneously rotating the several screw members selectively in either direction for swinging the supported clamps to their clamping positions and thereafter drawing them upwardly against said punch holder projecting portions to clamp the same or vice versa.

References Cited in the file of this patent UNITED STATES PATENTS 241,617 Chapman May 17, 1881 1,412,170 Dixon Apr. 11, 1922 2,22A,708 Sittert Dec. 4, 1940 2,695,788 Baier Nov. 30, 1954 2,755,758 Johansen July 24, 1956 FOREIGN PATENTS 605,008 Great Britain July 14, 1948 831,602 Germany Feb. 14, 1952 

